Optics made to measure

(Nanowerk News) If you are in the business of developing high-speed electronic components, it pays not to lose sight of the electrons. To keep track of them you will need to use dedicated optical elements, such as those now on offer from UltraFast Innovations GmbH. The new company, which has just been founded by researchers at Ludwig-Maximilians-Universität (LMU) in Munich and the Max Planck Society (MPG), manufactures specialized mirrors and other optical elements for use with pulsed laser light and x-rays. These components allow to generate and manipulate ultrashort light pulses. Pulses of extremely short duration, in turn, make it possible to observe the movement of the electrons in atoms and molecules in real time. Mirrors suitable for this purpose have only been commercially available to a limited extent until now. They will be of interest to companies that manufacture laser systems for industrial applications, as well as to research groups in the area of quantum and x-ray optics. LMU Munich and the MPG each have a 50 % stake in the new joint-venture.

Electrons are really fast – they can migrate from one atom to another within attoseconds (an attosecond is a billionth of a billionth fraction of a second). To observe such rapid movements, a highly refined optical set-up is needed that permits the production of extremely short light pulses. Components for such systems can now be fabricated to customer specifications by UltraFast Innovations GmbH.

The company offers an all-inclusive service, starting from the design of the elements to surface coating of mirrors and the quality inspection of their optical parameters. Mirror coatings can be optimized with respect to features such as high reflectivity, wide spectral bandwidth or a particular filter function. UltraFast Innovations GmbH is backed by the expertise of the participating scientists. The research teams led by Ferenc Krausz, director at the Max-Planck-Institute of Quantum Optics and professor at LMU, and Ulf Kleineberg, who is also a professor at LMU include leading experts in the field of specialized optics. Ferenc Krausz is regarded as one of the inventors of the so-called chirped mirror, a particular type of mirror that enables the creation of ultrashort laser pulses, and he is the holder of several patents on this technology.

Chirped mirrors allow one, for example, to compensate for the phenomenon of material-dependent dispersion, which occurs if the reflective surface delays light of different colors to different degrees – an effect that can increase pulse duration. Indeed, it was the ability of the chirped mirror to diminish this effect that first enabled the generation of ultrashort light pulses. With the aid of such mirrors, researchers were able, in 2008, to produce flashes that lasted for only 80 attoseconds, in this way breaking the 100-attosecond barrier for the first time, and creating the shortest light pulses ever generated in the laboratory. In 80 attoseconds light travels a distance of less than one thousandth of a millimeter.

"Such light pulses give us the opportunity to observe the movements of electrons in atoms and molecules in real time", explains Dr. Jens Rauschenberger, a member of Ferenc Krausz's research group and managing director of the new company. "It is like using a camera. To capture a sharp image of a fast-moving object, you need very short exposure times."

A better understanding of how electrons behave is of practical relevance for communication technologies, for example, and will help to further improve the efficiency of data processing. Short bursts of visible light are already being used for imaging techniques in medicine. Optical coherence tomography, for instance, is an important tool in ophthalmology, allowing one to examine the retina.

One especially notable aspect of UltraFast Innovations GmbH lies in its very close links with current basic research. "Since the development and manufacture of optical elements is an integral part of our scientific work, we can immediately incorporate the latest research results into our designs", says Jens Rauschenberger. "New optics can then immediately be subjected to practical tests." In addition, the establishment of UltraFast Innovations allows more efficient utilization of the high-precision coating facilities at the Service Center for Surface Coatings and Optics, which is part of the "Munich Centre for Advanced Photonics" (MAP). And the new firm also creates other benefits, according to Jens Rauschenberger: "Apart from enabling better utilization of existing technical capacities, we at UltraFast Innovations can also provide important new impulses for research activities, because the profits from the business can be reinvested in the scientific institutes, or used to finance new positions".